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Aggregation of Cu and Ni adatoms on oxygen preadsorbed Cu(100) was studied by STM. Cu deposited on a Cu(100) c(2×2)-O surface agglomerate into anisotropic islands with a (2 2 × 2 )R45°-O structure, while Ni deposited on a c(2×2)-O surface forms isotropic Ni islands with c(2×2)-O structure. On the other hand, Ni on a (2 2 × 2 )R45°-O structure undergoes extremely anisotropic aggregation, which forms Ni-wires with a c(2×2)-O structure. Formation of Ni-wire on a (2 2 × 2 )R45°-O structure has been inferred by a preferential nucleation along the Cu atom missing trough inlaid with Ni.

Nano-scale patterning of the metal surfaces was attained by the adsorption and the reaction of metal atoms. Growth of metal islands on the metal surfaces was markedly influenced by preparing the surface with preadsorption and/or by the reconstruction. Adsorption of oxygen on Cu(100) form randomly coalesced nano-size c(2 x 2)-O which undergoes the (2√2 x √2)R45° reconstruction with increasing the oxygen coverage. In contrast, N-atoms on Cu(100) make well ordered array of squared c(2 X 2)-N patches of ca. 50 A 2 . Cu atoms deposited on the nano-size c(2 X 2)-O Cu(100) form one atomic height rectangular Cu islands but Ni atoms undergo no orientational growth of Ni islands. Ni atoms deposited on the (2√2 x √2)R45°-C Cu(100) surface, however, gave an extremely anisotropic growth of Ni-wire. In contrast, when Ni atom was deposited on a Cu(100) surface having a super-grid like pattem made by the boundaries of squared c(2 x 2)-N patches, one atomic height Ni islands grew at the crossings of the super-grid. These phenomena are distinctive from the chemical reaction of surface atoms which provides various quasi-compounds. The reaction of Cu with (-Ag-O-) strings on Ag(110) provided a new quasi-compound of (-Cu-O-) on Ag(110), which undergoes a reversible reaction of (-Cu-O-)⇄ (Cu) 6 + O 2 . In addition, the (-Ag-O-) strings on Ag(110) undergo selective photo-erasing. These results suggest that chemical reaction is a promising tool for making atomic-scale pattern on the surface.